Slack published an open letter to Microsoft in the New York Times this week. Like a valedictorian’s speech, which, at the outset, promises the deliverance of sage advice, only to then slip into the rote listing of its scribe’s accomplishments, the letter was received by many as smarmy* condescension.

I, too, found the open letter a little cringe-inducing, not just because of its tone, but because of its contrast with another piece of Slack’s open writing, CEO Stewart Butterfield’s excellent memo “We Don’t Sell Saddles Here”.

WDSSH was a bugle blast. A rousing call-to-action for a team about to put something new into the world. The essay’s focus was the customer and how Slack could bring them into the new market they were defining. It mentioned the word “competitor” once. I didn’t work at Slack and I still felt inspired when I read its closing line: “The answer to Why? is because why the fuck else would you even want to be alive but to do things as well as you can?”

Maybe that’s why last week’s open letter was a disappointment. Because it signaled that Slack had moved on to worrying about competitors, not customers.

For that’s what the letter said more than anything else, that in spite of its explicit appeal to customers, it was implicitly still a letter to a competitor.

The irony is, as a user of Slack, I didn’t consider Microsoft in the same ballpark when it came to team messaging. Even with the announcement of Teams, I’d been through too much with Lync to assume they’d ever be a part of the enterprise collaboration conversation.

Well, they certainly are now.

*all credit due to the Verge’s Casey Newton for finding the perfect word for the tone of Slack’s open letter.